It is common practice for retail store and/or restaurants owners to paint windows with temporary and removable graphics. This type of graphic has great appeal and benefit as an advertising and promotional medium because the advertisement is displayed in the relevant location to relevant consumers (i.e., consumers outside the store and/or restaurant) and it can be changed frequently. Such graphics can be used on any glass or plastic surface, including e.g, windows, privacy screens, phone booths, bus windows, and storefronts. The popularity of this practice is evident—painted window graphics is one of the largest segments in the sign painting industry.
Yet traditional window graphics have limitations. They typically look poor from the inside of the window and block the light and view. Not being able to see out through the windows to monitor suspicious activity outside the business can have serious security problems for businesses such as banks, retail and convenience stores. Further, the paint for such graphics is typically applied to the window surface in layers of color, each color being built upon the previous color. Often multiple tools are used, including roller, airbrush, paintbrush, lettering stencils, spray equipment, or finger painting. Thus this method has the additional disadvantages of: (a) taking time and expense of skilled labor to create the displays, (b) being difficult to change and modify the graphic as desired, and (c) being difficult to clean up and remove of the graphic.
Retailers also use one-way graphic materials for store displays. One-way graphic materials are materials that have an image on one side, yet permit vision through the material from the other side. Optical properties are manipulated such that the material appears opaque from the image side, but appears substantially transparent when viewed from the non-image side. Generally, one-way graphic materials are light permeable, with one relatively dark side and one relatively light side. Images are typically placed on the light side of the one-way material. People viewing from that side will see the image. People viewing the material from the back side of the material do not see the image, but instead see the environment on the far side of the one-way graphic. Other forms of one-way graphics use transparent inks and/or retroreflective materials, and rely on differences in illumination and scale perception to create the same effect, with the image typically visible from the brighter, outdoor side of the window, while being substantially invisible from the darker, inner side of the window.
One-way graphics typically use perforated substrates, upon which an image is printed using digital printers or silk screening. Other methods of production of one-way graphics involve the application of “print patterns” of bonding material onto the surface of a transparent, non-bonding substrate, as in U.S. Pat. No. 6,267,052 (Hill et al.). Images may then be printed onto the “print pattern” of bonding material to create an image layer. One-way graphics can thus be made using non-perforated films (e.g., 3M™ Scotchcal™ Clear View Graphic Film IJ8150), wherein a print pattern simulating a perforated surface is used to create unprinted surfaces that simulate the effect of perforation.
The embodiments described above involve one-way graphic displays in which a single, permanent image is bonded to the surface of the one-way display. Because the one-way displays are entirely dye-based, as with standard window displays, they require the user to remove and replace a display each time the user wishes to display a different graphic image. Furthermore, existing technology for one-way graphic displays is entirely static, and does not allow for any movement of the image on the one-way graphic display. Thus, the current state of the art in one-way graphics also fails to take advantage of many of the advantages associated with motion pictures, television, and other video arts based on projection of images, where a single projection panel can be used to display many different types of images, and can portray motion.
Non-emissive dynamic display technologies are also known. One example is the electrophoretic display described in U.S. Pat. No. 5,930,026, commonly referred to as E Ink® This technology uses tiny microcapsules that are suspended in liquid placed within a film-like layer. The microcapsules contain both positively charged white particles and negatively charged black particles. Applying a negative electrical field to the microcapsules causes the white particles to come to the surface of the display. Conversely, applying a positive electrical field causes the black particles to come to the surface. By applying different fields at various parts of a screen, the technology produces a visual display. Besides being considered by many as easier on the eyes than emissive displays, E Ink® also boasts lower power consumption, particularly when compared to traditional backlit liquid crystal display (LCD) screens. More recent versions of E Ink include the ability to display color and multiple shades of grey. However, non-emissive displays have not been used in commercial displays, and have not been adapted to use in one-way graphic materials.
Accordingly, it is the object of the invention to provide graphic displays screens that (1) are suitable for use in commercial and retail window displays, (2) provide the opportunity to display graphics without substantially impeding vision out of windows, (3) allow easy introduction of new images without complete replacement of the display, (4) allow the user to display moving images, and (5) utilize energy efficiently. It is a further object of this invention to provide new forms of non-emissive displays using colored particulates.